Not closing panel problem

Vivaldi 1.3.534.3 windows 10 The panel (with download, notes etc) will NOT close pushing the small triangle in the center of the side of the panel. The panel WILL close with the help of F4 or pushing the black and white square on the bottom of the panel. John

The panel (with download, notes etc) will NOT close pushing the small triangle in the center of the side of the panel.
The panel WILL close with the help of F4 or pushing the black and white square on the bottom of the panel.